USB 3.1 cameras on USB 2 bus do not support images larger than 4 MB

Last Revision Date: 6/5/2014

This article discusses the issue of image size when using USB 3.1 Cameras on USB 2 bus.

For Windows versions XP through 8, the Microsoft USB 2 driver supports a maximum buffer size of 4 MB.

If you are using a Point Grey USB 3.1 camera with a USB 2 bus, the limitation of the USB 2 driver means your image sizes must be less than 4 MB. For cameras such as the Flea3 USB 3.1 32S2, this means that some modes will not work as expected.

To determine the image size:

Image size = resolution X pixel format in bytes per pixel 

Pixel Format  bytes/pixel 
12-bit 1.5 

For example, a 1280 x 960 RGB image is 3.7 MB. If the image size is larger than 4 MB maximum supported by the Microsoft USB 2 driver, adjust the image size to be smaller.

Point Grey recommends using a USB 3.1 card with USB 3.1 cameras to be able to take full advantage of all the cameras’ capabilities. See our accessories page for a list of products available from FLIR.

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